Machines of this general type are known having tools for working the soil consisting of disks having the shape of a spherical cap the edge of which is circular or ribbed. However, these known machines have several drawbacks.
A first drawback of the known machines resides in the fact that the smooth or ribbed disks cut the weeds, which causes them to proliferate. This proliferation is particularly significant in the case of couch grass. The elimination of this increased mass of weeds requires a very large volume of weed-killing products. This increases production costs and endangers the environment.
A second drawback of the disks equipping the known machines resides in the creation of a large plow sole which prevents or impedes the flow of water into the soil and the growth of the root system of plants. Moreover, in clayey soils, the disks cause a considerable smoothing of the clods, which is detrimental to their later breakup during the preparation of a seed bed. In addition, in clayey soils, the disks also have a tendency to clog very quickly. On the other hand, in loam soils, the disks cause a pulverization of the soil which promotes the formation of extremely hard harmful layers after precipitations.
A third drawback of the known machines resides in the fact that, in dry soils, the disks do not easily penetrate the soil, or even do not penetrate the soil at all.
A fourth drawback of the known machines relates to the obtaining of a poor mixture of straw and soil when plowing up the stubble of a field. This is mainly due to the fact that the disks have a relatively limited ability to throw the soil.
A fifth drawback of the known machines relates to the relatively rapid wear of the disks. Since the disks cut the soil, their thickness must necessarily be small, which brings about a rapid wear.